BRYOZOA FROM ZANZIBAR. 473 



wall. Usually, in Scru2:)ocellari(l£e, the inner zofficium of the new 

 pair is jointed close to the proximal end (PI. LXVIII. fig. 14), 

 but the position of the articulation of the outer zocecium varies 

 considerably, having the part below the articulation much larger 

 than the similar portion in the inner zocecium. There ai-e three 

 exceptions to this rule — Menipea cirrata Ell. & Sol., M. smittii* 

 ISTorm., M.Jlagellifera Busk — all three of which are without a 

 scutum t. 



A. — Beginning with what seems to me the simplest form of 

 articulation, namely, that found in Ganda retiformis Pourt. 

 (PI. LXIX. fig. 6), though both genus and species have previously 

 been described as non-articulated in consequence of the chitinous 

 tube being often entirely covered by the calcareous wall, in which 

 as yet there is no rupture, so that decalcification is necessary in 

 order to study the articulation. As mentioned on p. 480, in the 

 younger bi'anches no articulation is found, but in the older ones 

 there is a chitinous tube on the inside of one of the two branches 

 and a similar tube on the opposite side in the next branch, and 

 so on alternately (fig. 6). 



B. — From the simple form of Ganda, we pass on to that of 

 Scriqjocellaria with two chitinous tubes, but with the outer 

 zo(iecium having the articular tube near the middle of the 

 zooecium (PI. LXIX. fig. 8). As an example, S. jolloisii Aud. 



C — In the following group the chitinous tube in the outer 

 zocecium is very much lower than in B, but is not, however, close 

 to the proximal end of the zooecium. The articular tubes are 

 here narrower, more distinct, and often separated as in Menipea 

 ])atagonica Busk (PL LXIX. fig. 11). As examples, M. ternata 

 Ell. & Sol., Bagulopsis peachii Busk (PI. LXIX. fig. 10), M. occi- 

 dentalis Trask, M. porteri MacG. 



D. — We pass next to a group in which both articular chitinous 

 tubes are close to the proximal end of the zocecia. I spoke of 

 the proximal fends of these new zocecia as small chambers, but 

 now consider that it would be better to compare them with the 

 " basis rami " [Harmer) of Grisia, and think the designation may 

 be used here, remembering that they are really the beginnings of 

 new zooecia. As examples, Menipea buskii W. Th. (PI. LXIX. 

 fig. 12), M. crystallhia Gray, M. cervicornis MacG., M. occi- 

 dentalis Trask, M, cirrata Ell. »& Sol, 



* Waters, " Bryozoa from Franz Josef Land," Journ. Linn. Soc, ZooL vol. xxviii. 

 pi. vii. fi?. 8 (1900). 



t As I have alwa3's noticed the articulation when opportunities have presented 

 themselves, several have been carefully figured. In my paper on " Bryozoa froiu 

 Kapallo," Journ. Linn. Soc, Zool. vol. xxvi. pi. i. the position of the polypides in 

 the zooecia of Scrupocellaria iriermis is shown, figs. 11, 12, and op. cit. vol. xxviii., 

 the joints of Menipea gracilis, pi. vii. fig. 12, Scrupocellaria scabra, fisr. 14, and 

 S. smittii Norm., fig. 8, are shown. In the last the articulation only occurs 

 beyond the distal end of the outer zocecium. In the present paper the articulation 

 is shown in PI. LXVIII. fig. U. 



